Quartz glass crucible and process for the manufacture of the crucible

Abstract

To facilitate the start of a process using a quartz glass crucible with a crucible body and an inner layer of quartz glass a quartz glass crucible is provided with an inner surface roughened at least in the starting zone region by multiple depressions disposed at a maximum distance of 5 mm from one another. Furthermore, a simple and inexpensive process for the manufacture of such a quartz glass crucible is described, by providing a crucible body with a smooth inner surface of quartz glass and subsequently roughening the inner layer in the starting zone region by multiple depressions disposed at a maximum of 5 mm from one another.

What is claimed is:  
     
       1. A quartz glass crucible comprising: 
       a crucible body with an inner surface of quartz glass;  
       the inner surface comprising a roughened portion in a starting zone in said crucible, said roughened portion being roughened by multiple depressions therein; the multiple depressions being spaced from one another at a maximum distance of 5 mm; and  
       the inner surface outside of the starting zone being smoother than in said roughened portion, wherein said roughened portion in the starting zone is located in an upper third of the crucible.  
     
     
       2. The quartz glass crucible according to  claim 1 , wherein the depressions are separated by a maximum distance of 1 mm. 
     
     
       3. The quartz glass crucible according to  claim 1 , wherein the depressions are separated by a maximum distance of 100 μm. 
     
     
       4. The quartz glass crucible according to  claim 1 , wherein the inner surface is formed of synthetic quartz glass. 
     
     
       5. The quartz glass crucible according to  claim 1 , wherein said roughened portion of the inner surface has an etched structure. 
     
     
       6. The quartz glass crucible according to  claim 1 , wherein said roughened portion of the inner surface has a repeating impression pattern. 
     
     
       7. The quart glass crucible according to  claim 1 , wherein said roughened portion of the inner surface is scored so as to have scores therein. 
     
     
       8. The quartz glass crucible according to  claim 1 , wherein said roughened portion in the starting zone of the inner surface has a bubble zone in which the inner surface has open pores therein. 
     
     
       9. The quartz glass crucible according to  claim 1 , wherein, outside of the starting zone, the inner surface is fire polished. 
     
     
       10. A quartz glass crucible comprising: 
       a crucible body of quartz glass, said crucible body comprising an inner wall surface defining an interior space configured to receive a melt therein so that the melt has a melt surface at a starting zone of the inner wall surface extending around the melt surface;  
       the inner wall surface in the starting zone comprising a roughened portion that is roughened by multiple depressions therein, the multiple depressions being spaced from one another at a maximum distance of 5 mm, so that said inner wall surface is configured to provide the roughened portion, facing the melt surface, so that the roughened portion stabilizes the melt surface during a process pulling material therefrom, wherein said roughened portion in the starting zone is located in an upper third of the crucible.  
     
     
       11. The quartz glass crucible according to  claim 10 , wherein outside of the roughened portion, the inner wall surface is smoother than in the roughened portion. 
     
     
       12. The quartz glass crucible according to  claim 11 , wherein the inner wall surface outside the roughened portion thereof is smoothed by fire polishing. 
     
     
       13. The quartz glass crucible according to  claim 10 , wherein the roughened portion extends circumferentially completely around the melt surface. 
     
     
       14. The quartz glass crucible according to  claim 10 , wherein the depressions are separated by a maximum distance of 1 mm. 
     
     
       15. The quartz glass crucible according to  claim 10 , wherein the depressions are separated by a maximum distance of 100 μm. 
     
     
       16. The quartz glass crucible according to  claim 10 , wherein the inner wall surface is formed of synthetic quartz glass. 
     
     
       17. The quartz glass crucible according to  claim 10 , wherein said roughened portion of the inner wall surface has an etched structure. 
     
     
       18. The quartz glass crucible according to  claim 10 , wherein said roughened portion of the inner wall surface has a repeating impression pattern. 
     
     
       19. The quartz glass crucible according to  claim 10 , wherein said roughened portion of the inner wall surface is scored so as to have scores therein. 
     
     
       20. The quartz glass crucible according to  claim 10 , wherein said roughened portion in the starting zone of the inner wall surface has a bubble zone in which the inner wall surface has open pores therein.